1. Field of the Invention
The invention relates to a turbine insert insertable into the head of a dental turbine-elbow and includes a rotatable shaft provided with turbine blades, one end thereof being formed for receiving a dental tool, for example, a drill, the other end thereof being rotatably supported in a cap which may be screwed on the head housing by means of a bearing.
In the event of any damage to a turbine-insert of this type or a component thereof, the whole turbine-insert may be easily and quickly removed by unscrewing the cap from the head housing, and by replacing it with a new and undamaged turbine insert, which facilitates the repair of such a damage by the dentist or his assistant.
2. Description of the Prior Art
A well known turbine insert of this type is known in the prior art, in which the turbine blades as well as the side of the shaft carrying the tool and a bearing associated with the shaft are accessible when not inserted into the head housing, so that a special protective cap is required, for example, for transportation, in order to protect the accessible and sensitive parts from damage prior to the assembly being inserted into the head housing. Insertion into the head housing is furthermore difficult, since the accessible parts project laterally with respect to the shaft, and therefore may impinge on the walls of the head housing upon insertion thereinto and be damaged thereby. Damage of this kind renders the whole turbine insert useless. Furthermore impingement of the support associated with the tool portion of the shaft with the walls of the head housing may result in a displacement of that support and a change of its alignment with respect to the rotatable shaft, resulting in a misalignment, so that the rotatability and life span of the turbine-insert are impaired.
Although a turbine insert is known from Austrian Pat. No. 235,466 having a support disposed on the shaft facing away from the tool portion, and where the turbine blades are surrounded by respective ring-shaped housings, the support associated with the tool side, or facing the tool side, is also accessible in this known device, so that the latter is saddled with the same disadvantages. As a result of the use of the above-named ring-shaped housing, the turbine insert is open on the end thereof facing away from the tool portion, making it necessary for a special cover to be screwed onto the head of the housing upon insertion of the turbine-insert thereinto, so that the turbine-insert is clamped in an axial direction. This may lead to misalignment of the components of the turbine-insert. Furthermore the special cover results in a relatively large height of the closed head-housing, which causes difficulties in the mouth of a patient during treatment. The special cover may furthermore be lost.
Furthermore, there is known a turbine-insert from German prosecuted Pat. No. 1,061,063, in which the rotatable shaft and the adjacent supports are disposed in a cap which may be screwed onto the head housing, the cap being formed with an opening permitting the passage of the dental tool. The turbine blades disposed in this case on the portion of the rotatable shaft facing away from the tool may, however, be damaged during transport, or insertion of the turbine-insert into the head housing.